Device and method for wet treating disc-shaped articles

ABSTRACT

In a spin-chuck with plural collector levels, a separate exhaust controller is provided for each level. This permits selectively varying gas flow conditions among the collector levels, so that the ambient pressure at one level does not adversely affect device performance in an adjacent level.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of co-pending application Ser. No.10/549,620 filed on Dec. 4, 2006, which is the 35 U.S.C. §371 nationalstage of International PCT/IB2004/050238 filed on Mar. 12, 2004, whichclaims priority to Austrian Application No. A 444/2003 filed on Mar. 20,2003. The entire contents of each of the above-identified applicationsare hereby incorporated by reference. Any disclaimer that may haveoccurred during prosecution of the above referenced applications ishereby expressly disclaimed.

FIELD OF THE INVENTION

The invention relates to a device and a method for wet treating a flatplate-like substrate, such as semiconductor wafers, flat panel displaysor compact discs. The device comprising a spin-chuck for holding androtating the substrate, at least one dispenser for dispensing a liquidonto at least one surface of said substrate, a liquid collectorcircumferentially surrounding said spin-chuck for collecting liquid,which is spun off the substrate during rotation. The liquid collectorhas at least two collector levels. Each of the collector levels has thepurpose of separately collecting liquids in different collectors.

The device further comprises lifting means for moving spin-chuckrelative to liquid collector substantially along the rotation axis andat least two exhaust levels for separately collecting gas from theinterior of the liquid collector. Collecting gas from the interior ofthe liquid collector is useful to avoid deposition of mist beinggenerated when liquid is spun off the substrate.

BACKGROUND OF THE INVENTION

Such a liquid collector often is called a “cup” even though it does notnecessarily have a closed bottom. Another word often used for the liquidcollector is “chamber” even though it is not closed on all sides.

Such a device is known in the art and described in details in U.S. Pat.No. 4,903,717. This patent shows each collector of each collector levelbeing connected to a common exhaust. Each collector level therebysimultaneously serves as an exhaust level. Therefore while the commonexhaust is turned on gas is sucked from the interior of the liquidcollector by each exhaust level.

During processing it might happen that below the level of the spin-chuckthe gas pressure is lower than ambient gas pressure. Consequently liquidwhich is ought to be spun in to a specific collector level might bepartly sucked into the collector level below the selected collectorlevel.

If a liquid X is brought to a wrong collector level in which a differentliquid Y shall be collected liquid X will contaminate liquid Y. In theworst case liquids X and Y react with one another generating hazardousor flammable reaction products.

Another undesired result might happen if liquid Y is recycled in orderto treat as many substrates as possible. A contamination of liquid Ywith liquid X then might result in the destruction of the substratestreated thereafter. In this case another consequence could be asignificant decrease of the shelf life of liquid Y.

SUMMARY OF THE INVENTION

Thus it is an object of the invention to avoid liquid being partlysucked into the collector level not actually selected to collect thatliquid.

Another object of the invention is to decrease the necessary exhaustflow. This is not only because a high exhaust volume per time unitraises process cost, but also because too high exhaust sucks too muchliquid into the exhaust, which has the disadvantages of high liquidconsumption and of high afford for cleaning the exhausted air.

The invention meets the objects by providing a device for wet treating aflat platelike substrate comprising:

a spin-chuck for holding and rotating the substrate; at least onedispenser for dispensing a liquid onto at least one surface of saidsubstrate; a liquid collector circumferentially surrounding saidspin-chuck for collecting liquid, which is spun off the substrate duringrotation, with at least two collector levels, for separately collectingliquids in different collectors; lifting means for moving spin-chuckrelative to liquid collector substantially along the rotation axis; atleast two exhaust levels for separately collecting gas from the interiorof the liquid collector; at least one exhaust influencing means, whichis associated with at least one of said at least two exhaust levels, forselectively varying gas flow conditions in at least on of said at leasttwo exhaust levels.

The dispenser can be configured in different ways, e.g. so that liquidsprays onto a substrate or runs onto the substrate in a continuous,turbulence-free way. The dispenser can be configured either to bedirected towards the lower surface of a substrate when processed,therefore directed upwards, or towards the upper surface of a substratewhen processed, therefore directed downwards. In both cases thedispenser can be configured to be horizontally moved during processing.It is further possible to use dispensers of both configurations, whichallows to apply liquid onto both surfaces of the substrate even at thesame time.

The spin-chuck can for instance be a vacuum-chuck, a Bernoulli-chuck, achuck gripping the edge of the substrate only (edge contact only=EeG) ora combination of such types.

Each exhaust level comprises interiorly open suction orifices. Thesuction orifices may be an annularly arranged plurality of suctionnozzles. Another possibility is to provide one annular slit-shapednozzle. In any case it is advantageous to provide an annulargas-collecting chamber to circumferentially equalize gas flow conditionsin one and the same exhaust level.

An advantage of the invention is that a significant reduction of theexhausted volume is possible and that cross-contamination between twoneighboured collector levels can be avoided.

Optionally the device has exhaust influencing means, which are flowcontrol modulating valve, such as a butterfly valve. This allows notonly to shut off an exhaust level, but also to precisely lower gas flowin every exhaust level.

In an advantageous device the at least one exhaust influencing means isa closing valve, whereby one of the at least two exhaust levels can beclosed. Such a configuration allows an easier control.

In another embodiment the device comprises controlling means whereby theat least one exhaust influencing means is controlled in dependence ofthe relative position of spin-chuck to liquid collector. Although thiscan be carried out easily in a mechanic way by connecting exhaustinfluencing means direct with the lifting means this will typically bedone by a computer. In the latter case the computer receives informationabout the relative position of chuck to liquid collector either directlyfrom the lifting means or electronic detectors detect the position.

If the suction orifices of at least one of the exhaust levels areconnected to one of the two collector levels this collector level at thesame time serves as exhaust level. The gas is sucked from the interiorof the liquid collector into the collector level and therein separatedfrom the liquid.

Yet another embodiment has at least one of the at least two exhaustlevels arranged above or below of a collector level. In this case thecollector level only collects liquid and does not suck gas as well. Thisbrings the advantage that gas and liquid do not have to be separatedafter being collected.

Another aspect of the invention is a method of controlling the gas flowwithin a device for wet treating a flat plate-like substrate. The devicecomprises a spin-chuck for holding and rotating the substrate, at leastone dispenser for dispensing a liquid onto at least one surface of saidsubstrate, a liquid collector circumferentially surrounding saidspin-chuck for collecting liquid, which is spun of the substrate duringrotation. The liquid collector comprises at least two collector levelsfor separately collecting liquids. The device further comprises liftingmeans for moving spin-chuck relative to liquid collector substantiallyalong the rotation axis and at least two exhaust levels for separatelycollecting gas from the interior of the liquid collector. The method ischaracterized in selectively generating different gas flow conditions inat least two of said exhaust levels.

In an embodiment the different gas flow conditions are selected in a wayto achieve substantially the same gas pressure adjacent to the rotatingsubstrate above and below

Further details and advantages of the invention can be realized from thedetailed description of a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic cross section of a first embodiment of theinvention.

FIG. 2 shows a schematic cross section of a second embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a device 1 comprising a spin-chuck 2 for holding androtating a substrate W. The substrate has a first side WI and a secondside W2. The spin-chuck is connected to a gear motor unit 5 to berotated about its axis A. Dispense arm 3 is used for dispensing liquidonto the first surface WI of the substrate W.

A cup-like liquid collector 4 circumferentially surrounds the spin-chuck2. The liquid collector is mounted on a frame (not shown). Lifting meansH are provided to alter the spin-chuck position relative to the liquidcollector. Thus the spin-chuck can be lifted to each of the threecollector levels L1, L2 and L3. Each collector level L1, L2, L3comprises an annular duct 41, 42, 43 to have spun off liquid collectedtherein. An additional splash guard (not shown) can be used for eachcollector to allow spun off liquid to hit it at an acute angle andthereafter to be directed to the annular duct. Each annular duct41,42,43 is connected to a pipe 81,82,83 through which the collectedliquid is drained. Drained liquid can immediately be reused to bedispensed to the substrate or collected as waste liquid. Each collectorlevel L1, L2, L3 is for collecting different liquids. L1 is forcollecting rinse liquid (e.g. DI-water), L2 for acidic liquids and L3for basic liquids.

The dash dotted lines indicate the planes, where the substrate is to beplaced for spinning off the liquids into the different collector levels.

Above each collector level L1, L2, L3 an exhaust level E1, E2, E3 isarranged substantially parallel to the collector level. The exhaustlevels are indicated by dotted lines. Each exhaust level comprises aplurality of interiorly open annularly arranged suction orifices 21, 22,23. Each array of the plurality of suction orifices 21,22 or 23 isconnected to a separate ring-shaped gas-collecting chamber 11, 12, 13respectively.

Each gas-collecting chamber is sucked off via a pipe 61, 62, 63. In eachpipe 61,62, 63 is controlled by a valve 71, 72, 73. In the shownembodiment the valves are butterfly valves. This gives the advantagethat the valve does not have to be totally closed but can be almostclosed so that still a very small amount of gas can be sucked off inthat specific suction level.

Most of the gas flow (air) that is sucked from the interior 40 of theliquid collector is provided from above (first gas-flow F1). Additionalopenings are provided, which connect the interior of the liquidcollector below the chuck with the exterior. This results in a secondgas-flow F2, which is preferably feed with clean air either from thesurrounding clean room or from a separate source. Means for selectivelymodulating the second gas-flow can be provided.

The following table shows possible conditions for running the device 1as shown in FIG. 1:

TABLE 1 Chuck Position upper middle lower exhaust exhaust exhaust levelE1 level E2 level E3 upper collector level L1 100% open 80% open closed(FIG. 1) middle collector level L2  10% open 100% open   60% open lowercollector level L3 closed 10% open 100% open

A computer can automatically select the status of each exhaust level independence of the position of the chuck.

FIG. 2 shows a second embodiment of the invention similar to the firstembodiment with the following differences. The exhaust orifices 21,22,23are connected to the collector levels. Thus the collector levels L1, L2,L3 serve at the same time as exhaust levels E1, E2, E3. To equalizesuction conditions circumferentially around each exhaust level eacharray of suction orifices is connected to an annular gas-collectorchamber.

The following table shows possible conditions for running the device 1as shown in FIG. 2:

TABLE 2 Chuck Position upper middle lower exhaust exhaust exhaust levelE1 level E2 level E3 upper collector level L1 100% open 10% open closed(FIG. 1) middle collector level L2  10% open 100% open   10% open lowercollector level L3 closed 10% open 100% open

In order to separate gas sucked from a specific exhaust level (e.g. E2)from gas sucked by another exhaust level (e.g. E3) it is possible toconnect each exhaust level to a different exhaust system. Such anexhaust system may contain elements for neutralizing the gas, denoxing(removing NO) and/or removing liquid residues (mist).

When lowering the chuck 2 the gas volume 47 below the chuck 2 isreduced. Therefore to avoid discharging gas against the second gas flowF2 might it be necessary to temporarily open the lower gas exhaust levelor to generally increase exhaust flow E.

What is claimed is:
 1. Device for wet treating a substrate, comprising:a spin chuck for holding and rotating the substrate about a rotationaxis; at least one dispenser for dispensing a liquid onto at least onesurface of said substrate; a liquid collector circumferentiallysurrounding said spin chuck for collecting liquid, which is spun off thesubstrate during rotation, with at least two collector levels forseparately collecting liquids in different collectors; lifting means formoving said spin chuck relative to said liquid collector substantiallyalong said rotation axis; at least two exhaust levels for separatelycollecting gas from the interior of the liquid collector; at least oneexhaust influencing means, which is associated with said at least twoexhaust levels, for selectively varying gas flow conditions in said atleast two exhaust levels; and a computer that automatically sets anexhaust flow for each of said at least two exhaust levels based on avertical position of said spin chuck relative to said liquid collector.2. The device according to claim 1, wherein said at least one exhaustinfluencing means is a flow control modulating valve.
 3. The deviceaccording to claim 1, wherein said at least one exhaust influencingmeans is a closing valve, whereby one of said at least two exhaustlevels can be closed.
 4. The device according to claim 1, whereinsuction orifices of at least one of said at least two exhaust levels areconnected to one of said two collector levels.
 5. The device accordingto claim 1, wherein at least one of said at least two exhaust levels isarranged above or below one of said at least two collector levels.